First of all, you're going to need a publicly accessible website. This could be a static website hosted in S3, or it could be a dynamically generated website hosted in EC2. In fact, your website doesn't even need to be hosted in AWS in order to use CloudFront. As long as your website is publicly accessible, you should be good to go.
You'll also need to have the ability to modify the DNS records for your website. Instead of pointing to your web server (or S3 bucket), we'll eventually point them to CloudFront.